The basic concept of a magnetic tape reel comprised of two flanges connected to a central hub has been known for some time. For example, in U.S. Pat. No. 3,632,053 such a structure is shown.
An improvement to this basic structure was taught in U.S. Pat. No. 4,044,965 in which a box-like or caisson configuration was taught comprising a hub, ring for supporting the magnetic tape and flanges. The box-like structure was taught to have sufficient rigidity to avoid hub deformation and flange buckling, while the tape was being wound on the ring.
According to U.S. Pat. No. 4,044,965, it was taught that the flanges were to be welded to the central part of the reel on each side thereof proximate the ring and hub sections. The polystyrene, for example, parts would be ultrasonically welded to form a box-like structure which exhibited better resistance to compression produced by tape being wound on the support ring. The flanges presented rather small-dimensioned projections on the internal faces of the central part defining a substantially cylindrical welding surface to the side flanges.
Although the magnetic tape reel as disclosed in U.S. Pat. No. 4,044,965 represented an advance in the art, the design also posed certain problems and it is an object of the present invention to teach a novel magnetic tape reel which possesses the box-like structure and rigidity of the prior art without the drawbacks as explained below.
The primary disadvantages inherent in the structure taught in U.S. Pat. No. 4,044,965 is the substantial difficulty encountered by manufacturers of such a device in maintaining constancy throughout the circumference of the reel in achieving an acceptable weld. It is quite common to experience some part-to-part irregularities and flange-to-hub misalignments which would prevent full circumferential contact between the annular collars of the central part and the welding surfaces of the side flanges. The areas of weld contact between the central part and the flanges along their entire circumferential lengths are of a relatively small dimension and any part inconsistencies or processing misalignments many times result in inconsistent weld areas and resulting part rejection.